Video effects/manipulation library?

I've been trying to find a good library for manipulating video, for example, gluing clips together, addings captions, transitions between clips etc开发者_StackOverflow. So far I have no been able to find anything promising. If it runs on linux thats a plus, does not have to be free. To be clear, im looking for some form of api/library, not a video editing tool.

There are a couple of CLI tools that come to mind.

• FFmpeg: arguablely the most popular tool for such things, although it might not be exactly what you need:
• MEncoder: it does some interesting things
• VLC: Another popular and powerful tool